Ceramic insulating material



' Patented June 21, 1927.

UNITED STATES HAROLD H. .SORTWELL, OF TBENTON, NEW JERSEY, ASSIGNOB TO THE STAR PORCE- PATENT OFFICE.

LAIN COMPANY, 01 TRENTON, NEW JERSEY, A CORPORATION OF NEW JERSEY.

CERAMIC INSULATING MATERIAL.

No Drawing.

My invention relates'to ceramic material and more particularly to insulating material of the porcelain type. One object of my invention is the economic production of black insulating porcelain of good quality. My material gives insulators which are vitreous, yet mechanically strong and which resist abrasion, and are non-inflammable, and of high dielectric strength. It provides a black m porcelain which can be used in place of any hot or cold moulded composition insulation.

The material is made by the addition of certain coloring ingredients to a base or group of porcelain forming ingredients. These coloring ingredients are preferably mixtures of the oxides of chromium, cobalt, iron and manganese, and the chromate of iron, and iron ores high in the magnetic oxide of iron, and red burning clays. The mixtures may be calcined and fired at temperatures suitable for insulating porcelain 4 before being mixed with the porcelain-forming ingredients.

As porcelain-forming ingredients, I employ feldspar, flint and one or more kinds of clay-such as red burning clay, English China clay, kaolin, and ball clay. The coloring ingredients and the porcelain-forming ingredients are ground wet in a ball mill, filterpressed, dried, pulverized and formed by the usual dry press process and fired in the usual way. The following are three examples of mixtures of the coloring and porcelain-forming ingredients which form black porcelain compositions of the desired qualities:

Parts.

Black iron ore 45 Red burning clay Potters flint 15 Feldspar 5 Parts.

Red oxide of iron- 6 Chromate of iron 5 4 Cobalt oxide 5 Ball clay' 17 Application filed February 27, 1924. Serial No. 695,576.

I apply to the surface of this black body, a black vitreous covering which may be either an engobe (slip) or glaze by spraying just before the ware is fired. As an example of a suitable engobe I give the following:

Parts. Red oxide of iron 9 Cobalt oxide 5 Feldspar 16 Potters flint 25 English China clay 25 Ball clay 20 As an example of a suitable glaze I give the following:

Parts. Manganese oxide 2 Cobalt oxide 1. 3 Chromium oxide 1 Iron oxide i 2 Feldspar 40' Whiting 16 China cla 25 Potters int 19 What I claim is:

Black porcelain insulating material containingb parts of black ironore, 35 parts of red urmn clay, 15 parts of potters flint and 5 parts 0 feldspar.

In testimony whereof I have signed my name to this specification.

HAROLD H. SOR'IWELL. 

